Re: [Qemu-devel] [PATCH 6/8] pci: Simpler implementation of primary PCI bus

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, May 23, 2013 at 10:16:13PM +1000, David Gibson wrote:
> On Thu, May 23, 2013 at 02:01:57PM +0300, Michael S. Tsirkin wrote:
> > On Thu, May 09, 2013 at 10:31:10AM +1000, David Gibson wrote:
> > > Currently pci_get_primary_bus() searches the list of root buses for one
> > > with domain 0.  But since host buses are always registered with domain 0,
> > > this just amounts to finding the only PCI host bus.
> > > 
> > > This simplifies the implementation by defining the primary PCI bus to
> > > be the first one registered, using a global variable to track it.
> > > 
> > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > 
> > This is the only part that I dislike.
> > How about an explicit API to set the primary bus?
> > Let machine types set it.
> 
> I guess, though I was hoping to avoid changing every bit of platform
> code that sets up a PCI bus.

Yes, that's a lot of churn.
Maybe we don't need a primary bus at all?
If there's one root, it's simple: check
it's the only one and return.

> -- 
> David Gibson			| I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
> 				| _way_ _around_!
> http://www.ozlabs.org/~dgibson